The overall objective of Subproject 6 is to investigate thepossible link between anxiety disorders and altered vestibular processing. This is based on the observation that panic attack and phobic avoidance are often prevalent in patients who present with balance disorders. Conversely, these investigators note that there seems to be a high prelevance of vestibular and balance dysfunction observed in patients who present with panic disorder and agoraphobia. These investigators aim to use a case control design in which they will examine vestibular correlates of the manifestations proposed in patients with anxiety disorders. Four groups of patients (n = 30) and a group of normal control subjects will be incorporated into the design of this study. Vestibular parameters to be assessed include the lateral semicircular canal-ocular reflex, using earth vertical axis rotation, and the otolith-ocular reflex, using off vertical axis rotation. Additionally, visual dependence for upright balance will be examined. Finally, the role of proprioception will be inferred by examining the effect of sway referencing to support surfaces. The data to be obtained in the experiments incorporated into the design are clearly articulated and there is a strong data analysis plan. The physical resources relevant to this project seem to be in place and there is every expectation that the goals of this project are likely to be met.